This recommended practice is intended to serve as a procedure to verify the functional performance, design specifications or vendor claims of any PEM (Proton Exchange Membrane) type fuel cell stack sub-system for automotive applications. In this document, definitions, specifications, and methods for the functional performance characterization of the fuel cell stack sub-system are provided. The functional performance characterization includes evaluating electrical outputs and controlling fluid inputs and outputs based on the test boundary defined in this document. In this document, a fuel cell stack sub-system is defined to include the following:

• Fuel cell stack(s) – An assembly of membrane electrode assemblies (MEA), current collectors, separator plates, cooling plates, manifolds, and a supporting structure.
• Connections for conducting fuels, oxidants, cooling media, inert gases and exhausts.
• Electrical connections for the power delivered by the stack sub-system.
• Devices for monitoring electrical loads.
• Devices for monitoring cell voltage.
• Humidification devices.
• Instrumentation for detecting normal and/or abnormal operating conditions.
• Enclosures (that may qualify as pressure vessels), and ventilation systems for the enclosure.

Not included in the sub-system are the following:

• Fuel and air processors
• Thermal management system
• Power conditioner and distributor
• Controllers